//rem设置
(function(doc, win) {
	var docEl = doc.documentElement,
		resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
		recalc = function() {
			var clientWidth = docEl.clientWidth;
			if (!clientWidth) return;
			docEl.style.fontSize = 20 * (clientWidth / 320) + 'px';
			//宽与高度
			document.body.style.height = clientWidth * (900 / 1440) + "px"
		};
	win.addEventListener(resizeEvt, recalc, false);
	doc.addEventListener('DOMContentLoaded', recalc, false);
})(document, window);